Arduino UNO R4 - Button - LED
This tutorial teaches you how to use the Arduino UNO R4 and a button to control an LED. We will learn two different ways to do this:
Application 1 - The LED follows the button's state:
- The Arduino UNO R4 turns on the LED when the button is pressed.
- The Arduino UNO R4 turns off the LED when the button is not pressed.
Application 2 - The LED changes its state each time the button is pressed:
- If the Arduino UNO R4 detects that the button has been pressed (changing from HIGH to LOW), it will turn the LED on if it is off, or turn it off if it is on.
- Releasing the button does not change the LED's state.
For Application 2, we need to debounce the button to make sure it works correctly. We will see why this is important by comparing how the LED behaves with and without debouncing in the Arduino code.
Hardware Preparation
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some of these links are for products from our own brand, DIYables.
Wiring Diagram
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Application 1 - The LED follows the button's state
Arduino UNO R4 Code
/*
* This Arduino UNO R4 code was developed by newbiely.com
*
* This Arduino UNO R4 code is made available for public use without any restriction
*
* For comprehensive instructions and wiring diagrams, please visit:
* https://newbiely.com/tutorials/arduino-uno-r4/arduino-uno-r4-button-led
*/
#define BUTTON_PIN 7 // The Arduino UNO R4 pin connected to the button
#define LED_PIN 3 // The Arduino UNO R4 pin connected to the LED
void setup() {
Serial.begin(9600); // initialize serial
pinMode(BUTTON_PIN, INPUT_PULLUP); // set arduino pin to input pull-up mode
pinMode(LED_PIN, OUTPUT); // set arduino pin to output mode
}
void loop() {
int buttonState = digitalRead(BUTTON_PIN); // read new state
if (buttonState == LOW) {
Serial.println("The button is being pressed");
digitalWrite(LED_PIN, HIGH); // turn on
}
else
if (buttonState == HIGH) {
Serial.println("The button is unpressed");
digitalWrite(LED_PIN, LOW); // turn off
}
}
Detailed Instructions
Follow these instructions step by step:
- If this is your first time using the Arduino Uno R4 WiFi/Minima, refer to the tutorial on setting up the environment for Arduino Uno R4 WiFi/Minima in the Arduino IDE.
- Wire the components according to the provided diagram.
- Connect the Arduino Uno R4 board to your computer using a USB cable.
- Launch the Arduino IDE on your computer.
- Select the appropriate Arduino Uno R4 board (e.g., Arduino Uno R4 WiFi) and COM port.
- Copy the code and open it in the Arduino IDE.
- Click the Upload button on the Arduino IDE to compile and upload the code to the Arduino UNO R4.
- Press the button and hold it for a few seconds.
- Check out the alteration in the LED's condition.
You will see that the LED state is in sync with the button state.
Code Explanation
Check out the line-by-line explanation contained in the comments of the source code!